Amphiphilic molecules, molecules containing a polar headgroup and a hydrophobic tail, dispersed in a selective solvent adopt structures that reflect a delicate balance between the interfacial energies of the solvated polar headgroup and the hydrophobic tail. The aggregation behavior of dispersed amphiphiles becomes considerably more complex as the overall surfactant molecular weight increases. Aqueous dispersions of amphiphilic block copolymers (ABCs) adopt complex morphologies as compared to conventional low molecular weight surfactants. In addition to spherical micelles, worm-like micelles, and vesicles, non-ionic macromolecular surfactants may form complex branched structures in dilute solutions. The vanishingly small critical micelle concentration, above which the surfactant molecules aggregate, kinetically traps temporally persistent ABC aggregates whose structures dramatically alter the rheological properties and wetting properties of the dispersant phase. Therefore, the utility of ABC dispersions depends critically on the ability to delicately control interfacial curvature between the hydrophilic and hydrophobic blocks using a combination of polymer composition, overall polymer molecular weight, and non-covalent interactions. By virtue of their ability to form persistent, solvated, nano-scale aggregates, macromolecular amphiphiles are widely employed as additives in personal care products, templated mesoporous materials syntheses, and in enhanced oil recovery.
Widespread non-ionic block copolymer surfactants utilize poly(ethylene oxide) (PEO) as the hydrophilic segment, however, this biocompatible polymer is not easily degraded. The development of degradable materials with the added benefit of biocompatibility and programmable degradation profiles would enable their widespread use in a variety of applications, including new materials for small molecule drug delivery, therapeutic nucleic acid delivery, tissue scaffolds with properties reminiscent of the extracellular matrix, new rheological modifiers for stabilizing emulsions, and viscoelastic surfactants for enhanced oil recovery. Poly(vinyl alcohol) is a water soluble polymer that is degradable both in the environment and under biological conditions in vivo, which is listed on the U.S. FDA “Generally Regarded as Safe” listing for use in various products fit for human consumption.